Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1502 insertions, 0 deletions

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
new file mode 100644
index 000000000..1150aa90e
--- /dev/null
+++ b/drivers/dma/stm32-dma.c
@@ -0,0 +1,1502 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for STM32 DMA controller
+ *
+ * Inspired by dma-jz4740.c and tegra20-apb-dma.c
+ *
+ * Copyright (C) M'boumba Cedric Madianga 2015
+ * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
+ *         Pierre-Yves Mordret <pierre-yves.mordret@st.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/iopoll.h>
+#include <linux/jiffies.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include "virt-dma.h"
+
+#define STM32_DMA_LISR			0x0000 /* DMA Low Int Status Reg */
+#define STM32_DMA_HISR			0x0004 /* DMA High Int Status Reg */
+#define STM32_DMA_LIFCR			0x0008 /* DMA Low Int Flag Clear Reg */
+#define STM32_DMA_HIFCR			0x000c /* DMA High Int Flag Clear Reg */
+#define STM32_DMA_TCI			BIT(5) /* Transfer Complete Interrupt */
+#define STM32_DMA_HTI			BIT(4) /* Half Transfer Interrupt */
+#define STM32_DMA_TEI			BIT(3) /* Transfer Error Interrupt */
+#define STM32_DMA_DMEI			BIT(2) /* Direct Mode Error Interrupt */
+#define STM32_DMA_FEI			BIT(0) /* FIFO Error Interrupt */
+#define STM32_DMA_MASKI			(STM32_DMA_TCI \
+					 | STM32_DMA_TEI \
+					 | STM32_DMA_DMEI \
+					 | STM32_DMA_FEI)
+
+/* DMA Stream x Configuration Register */
+#define STM32_DMA_SCR(x)		(0x0010 + 0x18 * (x)) /* x = 0..7 */
+#define STM32_DMA_SCR_REQ(n)		((n & 0x7) << 25)
+#define STM32_DMA_SCR_MBURST_MASK	GENMASK(24, 23)
+#define STM32_DMA_SCR_MBURST(n)	        ((n & 0x3) << 23)
+#define STM32_DMA_SCR_PBURST_MASK	GENMASK(22, 21)
+#define STM32_DMA_SCR_PBURST(n)	        ((n & 0x3) << 21)
+#define STM32_DMA_SCR_PL_MASK		GENMASK(17, 16)
+#define STM32_DMA_SCR_PL(n)		((n & 0x3) << 16)
+#define STM32_DMA_SCR_MSIZE_MASK	GENMASK(14, 13)
+#define STM32_DMA_SCR_MSIZE(n)		((n & 0x3) << 13)
+#define STM32_DMA_SCR_PSIZE_MASK	GENMASK(12, 11)
+#define STM32_DMA_SCR_PSIZE(n)		((n & 0x3) << 11)
+#define STM32_DMA_SCR_PSIZE_GET(n)	((n & STM32_DMA_SCR_PSIZE_MASK) >> 11)
+#define STM32_DMA_SCR_DIR_MASK		GENMASK(7, 6)
+#define STM32_DMA_SCR_DIR(n)		((n & 0x3) << 6)
+#define STM32_DMA_SCR_CT		BIT(19) /* Target in double buffer */
+#define STM32_DMA_SCR_DBM		BIT(18) /* Double Buffer Mode */
+#define STM32_DMA_SCR_PINCOS		BIT(15) /* Peripheral inc offset size */
+#define STM32_DMA_SCR_MINC		BIT(10) /* Memory increment mode */
+#define STM32_DMA_SCR_PINC		BIT(9) /* Peripheral increment mode */
+#define STM32_DMA_SCR_CIRC		BIT(8) /* Circular mode */
+#define STM32_DMA_SCR_PFCTRL		BIT(5) /* Peripheral Flow Controller */
+#define STM32_DMA_SCR_TCIE		BIT(4) /* Transfer Complete Int Enable
+						*/
+#define STM32_DMA_SCR_TEIE		BIT(2) /* Transfer Error Int Enable */
+#define STM32_DMA_SCR_DMEIE		BIT(1) /* Direct Mode Err Int Enable */
+#define STM32_DMA_SCR_EN		BIT(0) /* Stream Enable */
+#define STM32_DMA_SCR_CFG_MASK		(STM32_DMA_SCR_PINC \
+					| STM32_DMA_SCR_MINC \
+					| STM32_DMA_SCR_PINCOS \
+					| STM32_DMA_SCR_PL_MASK)
+#define STM32_DMA_SCR_IRQ_MASK		(STM32_DMA_SCR_TCIE \
+					| STM32_DMA_SCR_TEIE \
+					| STM32_DMA_SCR_DMEIE)
+
+/* DMA Stream x number of data register */
+#define STM32_DMA_SNDTR(x)		(0x0014 + 0x18 * (x))
+
+/* DMA stream peripheral address register */
+#define STM32_DMA_SPAR(x)		(0x0018 + 0x18 * (x))
+
+/* DMA stream x memory 0 address register */
+#define STM32_DMA_SM0AR(x)		(0x001c + 0x18 * (x))
+
+/* DMA stream x memory 1 address register */
+#define STM32_DMA_SM1AR(x)		(0x0020 + 0x18 * (x))
+
+/* DMA stream x FIFO control register */
+#define STM32_DMA_SFCR(x)		(0x0024 + 0x18 * (x))
+#define STM32_DMA_SFCR_FTH_MASK		GENMASK(1, 0)
+#define STM32_DMA_SFCR_FTH(n)		(n & STM32_DMA_SFCR_FTH_MASK)
+#define STM32_DMA_SFCR_FEIE		BIT(7) /* FIFO error interrupt enable */
+#define STM32_DMA_SFCR_DMDIS		BIT(2) /* Direct mode disable */
+#define STM32_DMA_SFCR_MASK		(STM32_DMA_SFCR_FEIE \
+					| STM32_DMA_SFCR_DMDIS)
+
+/* DMA direction */
+#define STM32_DMA_DEV_TO_MEM		0x00
+#define	STM32_DMA_MEM_TO_DEV		0x01
+#define	STM32_DMA_MEM_TO_MEM		0x02
+
+/* DMA priority level */
+#define STM32_DMA_PRIORITY_LOW		0x00
+#define STM32_DMA_PRIORITY_MEDIUM	0x01
+#define STM32_DMA_PRIORITY_HIGH		0x02
+#define STM32_DMA_PRIORITY_VERY_HIGH	0x03
+
+/* DMA FIFO threshold selection */
+#define STM32_DMA_FIFO_THRESHOLD_1QUARTERFULL		0x00
+#define STM32_DMA_FIFO_THRESHOLD_HALFFULL		0x01
+#define STM32_DMA_FIFO_THRESHOLD_3QUARTERSFULL		0x02
+#define STM32_DMA_FIFO_THRESHOLD_FULL			0x03
+#define STM32_DMA_FIFO_THRESHOLD_NONE			0x04
+
+#define STM32_DMA_MAX_DATA_ITEMS	0xffff
+/*
+ * Valid transfer starts from @0 to @0xFFFE leading to unaligned scatter
+ * gather at boundary. Thus it's safer to round down this value on FIFO
+ * size (16 Bytes)
+ */
+#define STM32_DMA_ALIGNED_MAX_DATA_ITEMS	\
+	ALIGN_DOWN(STM32_DMA_MAX_DATA_ITEMS, 16)
+#define STM32_DMA_MAX_CHANNELS		0x08
+#define STM32_DMA_MAX_REQUEST_ID	0x08
+#define STM32_DMA_MAX_DATA_PARAM	0x03
+#define STM32_DMA_FIFO_SIZE		16	/* FIFO is 16 bytes */
+#define STM32_DMA_MIN_BURST		4
+#define STM32_DMA_MAX_BURST		16
+
+/* DMA Features */
+#define STM32_DMA_THRESHOLD_FTR_MASK	GENMASK(1, 0)
+#define STM32_DMA_THRESHOLD_FTR_GET(n)	((n) & STM32_DMA_THRESHOLD_FTR_MASK)
+#define STM32_DMA_DIRECT_MODE_MASK	BIT(2)
+#define STM32_DMA_DIRECT_MODE_GET(n)	(((n) & STM32_DMA_DIRECT_MODE_MASK) \
+					 >> 2)
+
+enum stm32_dma_width {
+	STM32_DMA_BYTE,
+	STM32_DMA_HALF_WORD,
+	STM32_DMA_WORD,
+};
+
+enum stm32_dma_burst_size {
+	STM32_DMA_BURST_SINGLE,
+	STM32_DMA_BURST_INCR4,
+	STM32_DMA_BURST_INCR8,
+	STM32_DMA_BURST_INCR16,
+};
+
+/**
+ * struct stm32_dma_cfg - STM32 DMA custom configuration
+ * @channel_id: channel ID
+ * @request_line: DMA request
+ * @stream_config: 32bit mask specifying the DMA channel configuration
+ * @features: 32bit mask specifying the DMA Feature list
+ */
+struct stm32_dma_cfg {
+	u32 channel_id;
+	u32 request_line;
+	u32 stream_config;
+	u32 features;
+};
+
+struct stm32_dma_chan_reg {
+	u32 dma_lisr;
+	u32 dma_hisr;
+	u32 dma_lifcr;
+	u32 dma_hifcr;
+	u32 dma_scr;
+	u32 dma_sndtr;
+	u32 dma_spar;
+	u32 dma_sm0ar;
+	u32 dma_sm1ar;
+	u32 dma_sfcr;
+};
+
+struct stm32_dma_sg_req {
+	u32 len;
+	struct stm32_dma_chan_reg chan_reg;
+};
+
+struct stm32_dma_desc {
+	struct virt_dma_desc vdesc;
+	bool cyclic;
+	u32 num_sgs;
+	struct stm32_dma_sg_req sg_req[];
+};
+
+struct stm32_dma_chan {
+	struct virt_dma_chan vchan;
+	bool config_init;
+	bool busy;
+	u32 id;
+	u32 irq;
+	struct stm32_dma_desc *desc;
+	u32 next_sg;
+	struct dma_slave_config	dma_sconfig;
+	struct stm32_dma_chan_reg chan_reg;
+	u32 threshold;
+	u32 mem_burst;
+	u32 mem_width;
+};
+
+struct stm32_dma_device {
+	struct dma_device ddev;
+	void __iomem *base;
+	struct clk *clk;
+	bool mem2mem;
+	struct stm32_dma_chan chan[STM32_DMA_MAX_CHANNELS];
+};
+
+static struct stm32_dma_device *stm32_dma_get_dev(struct stm32_dma_chan *chan)
+{
+	return container_of(chan->vchan.chan.device, struct stm32_dma_device,
+			    ddev);
+}
+
+static struct stm32_dma_chan *to_stm32_dma_chan(struct dma_chan *c)
+{
+	return container_of(c, struct stm32_dma_chan, vchan.chan);
+}
+
+static struct stm32_dma_desc *to_stm32_dma_desc(struct virt_dma_desc *vdesc)
+{
+	return container_of(vdesc, struct stm32_dma_desc, vdesc);
+}
+
+static struct device *chan2dev(struct stm32_dma_chan *chan)
+{
+	return &chan->vchan.chan.dev->device;
+}
+
+static u32 stm32_dma_read(struct stm32_dma_device *dmadev, u32 reg)
+{
+	return readl_relaxed(dmadev->base + reg);
+}
+
+static void stm32_dma_write(struct stm32_dma_device *dmadev, u32 reg, u32 val)
+{
+	writel_relaxed(val, dmadev->base + reg);
+}
+
+static int stm32_dma_get_width(struct stm32_dma_chan *chan,
+			       enum dma_slave_buswidth width)
+{
+	switch (width) {
+	case DMA_SLAVE_BUSWIDTH_1_BYTE:
+		return STM32_DMA_BYTE;
+	case DMA_SLAVE_BUSWIDTH_2_BYTES:
+		return STM32_DMA_HALF_WORD;
+	case DMA_SLAVE_BUSWIDTH_4_BYTES:
+		return STM32_DMA_WORD;
+	default:
+		dev_err(chan2dev(chan), "Dma bus width not supported\n");
+		return -EINVAL;
+	}
+}
+
+static enum dma_slave_buswidth stm32_dma_get_max_width(u32 buf_len,
+						       u32 threshold)
+{
+	enum dma_slave_buswidth max_width;
+
+	if (threshold == STM32_DMA_FIFO_THRESHOLD_FULL)
+		max_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	else
+		max_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+
+	while ((buf_len < max_width  || buf_len % max_width) &&
+	       max_width > DMA_SLAVE_BUSWIDTH_1_BYTE)
+		max_width = max_width >> 1;
+
+	return max_width;
+}
+
+static bool stm32_dma_fifo_threshold_is_allowed(u32 burst, u32 threshold,
+						enum dma_slave_buswidth width)
+{
+	u32 remaining;
+
+	if (threshold == STM32_DMA_FIFO_THRESHOLD_NONE)
+		return false;
+
+	if (width != DMA_SLAVE_BUSWIDTH_UNDEFINED) {
+		if (burst != 0) {
+			/*
+			 * If number of beats fit in several whole bursts
+			 * this configuration is allowed.
+			 */
+			remaining = ((STM32_DMA_FIFO_SIZE / width) *
+				     (threshold + 1) / 4) % burst;
+
+			if (remaining == 0)
+				return true;
+		} else {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static bool stm32_dma_is_burst_possible(u32 buf_len, u32 threshold)
+{
+	/* If FIFO direct mode, burst is not possible */
+	if (threshold == STM32_DMA_FIFO_THRESHOLD_NONE)
+		return false;
+
+	/*
+	 * Buffer or period length has to be aligned on FIFO depth.
+	 * Otherwise bytes may be stuck within FIFO at buffer or period
+	 * length.
+	 */
+	return ((buf_len % ((threshold + 1) * 4)) == 0);
+}
+
+static u32 stm32_dma_get_best_burst(u32 buf_len, u32 max_burst, u32 threshold,
+				    enum dma_slave_buswidth width)
+{
+	u32 best_burst = max_burst;
+
+	if (best_burst == 1 || !stm32_dma_is_burst_possible(buf_len, threshold))
+		return 0;
+
+	while ((buf_len < best_burst * width && best_burst > 1) ||
+	       !stm32_dma_fifo_threshold_is_allowed(best_burst, threshold,
+						    width)) {
+		if (best_burst > STM32_DMA_MIN_BURST)
+			best_burst = best_burst >> 1;
+		else
+			best_burst = 0;
+	}
+
+	return best_burst;
+}
+
+static int stm32_dma_get_burst(struct stm32_dma_chan *chan, u32 maxburst)
+{
+	switch (maxburst) {
+	case 0:
+	case 1:
+		return STM32_DMA_BURST_SINGLE;
+	case 4:
+		return STM32_DMA_BURST_INCR4;
+	case 8:
+		return STM32_DMA_BURST_INCR8;
+	case 16:
+		return STM32_DMA_BURST_INCR16;
+	default:
+		dev_err(chan2dev(chan), "Dma burst size not supported\n");
+		return -EINVAL;
+	}
+}
+
+static void stm32_dma_set_fifo_config(struct stm32_dma_chan *chan,
+				      u32 src_burst, u32 dst_burst)
+{
+	chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_MASK;
+	chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_DMEIE;
+
+	if (!src_burst && !dst_burst) {
+		/* Using direct mode */
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_DMEIE;
+	} else {
+		/* Using FIFO mode */
+		chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_MASK;
+	}
+}
+
+static int stm32_dma_slave_config(struct dma_chan *c,
+				  struct dma_slave_config *config)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+
+	memcpy(&chan->dma_sconfig, config, sizeof(*config));
+
+	chan->config_init = true;
+
+	return 0;
+}
+
+static u32 stm32_dma_irq_status(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 flags, dma_isr;
+
+	/*
+	 * Read "flags" from DMA_xISR register corresponding to the selected
+	 * DMA channel at the correct bit offset inside that register.
+	 *
+	 * If (ch % 4) is 2 or 3, left shift the mask by 16 bits.
+	 * If (ch % 4) is 1 or 3, additionally left shift the mask by 6 bits.
+	 */
+
+	if (chan->id & 4)
+		dma_isr = stm32_dma_read(dmadev, STM32_DMA_HISR);
+	else
+		dma_isr = stm32_dma_read(dmadev, STM32_DMA_LISR);
+
+	flags = dma_isr >> (((chan->id & 2) << 3) | ((chan->id & 1) * 6));
+
+	return flags & STM32_DMA_MASKI;
+}
+
+static void stm32_dma_irq_clear(struct stm32_dma_chan *chan, u32 flags)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 dma_ifcr;
+
+	/*
+	 * Write "flags" to the DMA_xIFCR register corresponding to the selected
+	 * DMA channel at the correct bit offset inside that register.
+	 *
+	 * If (ch % 4) is 2 or 3, left shift the mask by 16 bits.
+	 * If (ch % 4) is 1 or 3, additionally left shift the mask by 6 bits.
+	 */
+	flags &= STM32_DMA_MASKI;
+	dma_ifcr = flags << (((chan->id & 2) << 3) | ((chan->id & 1) * 6));
+
+	if (chan->id & 4)
+		stm32_dma_write(dmadev, STM32_DMA_HIFCR, dma_ifcr);
+	else
+		stm32_dma_write(dmadev, STM32_DMA_LIFCR, dma_ifcr);
+}
+
+static int stm32_dma_disable_chan(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 dma_scr, id, reg;
+
+	id = chan->id;
+	reg = STM32_DMA_SCR(id);
+	dma_scr = stm32_dma_read(dmadev, reg);
+
+	if (dma_scr & STM32_DMA_SCR_EN) {
+		dma_scr &= ~STM32_DMA_SCR_EN;
+		stm32_dma_write(dmadev, reg, dma_scr);
+
+		return readl_relaxed_poll_timeout_atomic(dmadev->base + reg,
+					dma_scr, !(dma_scr & STM32_DMA_SCR_EN),
+					10, 1000000);
+	}
+
+	return 0;
+}
+
+static void stm32_dma_stop(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 dma_scr, dma_sfcr, status;
+	int ret;
+
+	/* Disable interrupts */
+	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+	dma_scr &= ~STM32_DMA_SCR_IRQ_MASK;
+	stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), dma_scr);
+	dma_sfcr = stm32_dma_read(dmadev, STM32_DMA_SFCR(chan->id));
+	dma_sfcr &= ~STM32_DMA_SFCR_FEIE;
+	stm32_dma_write(dmadev, STM32_DMA_SFCR(chan->id), dma_sfcr);
+
+	/* Disable DMA */
+	ret = stm32_dma_disable_chan(chan);
+	if (ret < 0)
+		return;
+
+	/* Clear interrupt status if it is there */
+	status = stm32_dma_irq_status(chan);
+	if (status) {
+		dev_dbg(chan2dev(chan), "%s(): clearing interrupt: 0x%08x\n",
+			__func__, status);
+		stm32_dma_irq_clear(chan, status);
+	}
+
+	chan->busy = false;
+}
+
+static int stm32_dma_terminate_all(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+
+	if (chan->desc) {
+		vchan_terminate_vdesc(&chan->desc->vdesc);
+		if (chan->busy)
+			stm32_dma_stop(chan);
+		chan->desc = NULL;
+	}
+
+	vchan_get_all_descriptors(&chan->vchan, &head);
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+	vchan_dma_desc_free_list(&chan->vchan, &head);
+
+	return 0;
+}
+
+static void stm32_dma_synchronize(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+
+	vchan_synchronize(&chan->vchan);
+}
+
+static void stm32_dma_dump_reg(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+	u32 ndtr = stm32_dma_read(dmadev, STM32_DMA_SNDTR(chan->id));
+	u32 spar = stm32_dma_read(dmadev, STM32_DMA_SPAR(chan->id));
+	u32 sm0ar = stm32_dma_read(dmadev, STM32_DMA_SM0AR(chan->id));
+	u32 sm1ar = stm32_dma_read(dmadev, STM32_DMA_SM1AR(chan->id));
+	u32 sfcr = stm32_dma_read(dmadev, STM32_DMA_SFCR(chan->id));
+
+	dev_dbg(chan2dev(chan), "SCR:   0x%08x\n", scr);
+	dev_dbg(chan2dev(chan), "NDTR:  0x%08x\n", ndtr);
+	dev_dbg(chan2dev(chan), "SPAR:  0x%08x\n", spar);
+	dev_dbg(chan2dev(chan), "SM0AR: 0x%08x\n", sm0ar);
+	dev_dbg(chan2dev(chan), "SM1AR: 0x%08x\n", sm1ar);
+	dev_dbg(chan2dev(chan), "SFCR:  0x%08x\n", sfcr);
+}
+
+static void stm32_dma_configure_next_sg(struct stm32_dma_chan *chan);
+
+static void stm32_dma_start_transfer(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	struct virt_dma_desc *vdesc;
+	struct stm32_dma_sg_req *sg_req;
+	struct stm32_dma_chan_reg *reg;
+	u32 status;
+	int ret;
+
+	ret = stm32_dma_disable_chan(chan);
+	if (ret < 0)
+		return;
+
+	if (!chan->desc) {
+		vdesc = vchan_next_desc(&chan->vchan);
+		if (!vdesc)
+			return;
+
+		list_del(&vdesc->node);
+
+		chan->desc = to_stm32_dma_desc(vdesc);
+		chan->next_sg = 0;
+	}
+
+	if (chan->next_sg == chan->desc->num_sgs)
+		chan->next_sg = 0;
+
+	sg_req = &chan->desc->sg_req[chan->next_sg];
+	reg = &sg_req->chan_reg;
+
+	reg->dma_scr &= ~STM32_DMA_SCR_EN;
+	stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), reg->dma_scr);
+	stm32_dma_write(dmadev, STM32_DMA_SPAR(chan->id), reg->dma_spar);
+	stm32_dma_write(dmadev, STM32_DMA_SM0AR(chan->id), reg->dma_sm0ar);
+	stm32_dma_write(dmadev, STM32_DMA_SFCR(chan->id), reg->dma_sfcr);
+	stm32_dma_write(dmadev, STM32_DMA_SM1AR(chan->id), reg->dma_sm1ar);
+	stm32_dma_write(dmadev, STM32_DMA_SNDTR(chan->id), reg->dma_sndtr);
+
+	chan->next_sg++;
+
+	/* Clear interrupt status if it is there */
+	status = stm32_dma_irq_status(chan);
+	if (status)
+		stm32_dma_irq_clear(chan, status);
+
+	if (chan->desc->cyclic)
+		stm32_dma_configure_next_sg(chan);
+
+	stm32_dma_dump_reg(chan);
+
+	/* Start DMA */
+	reg->dma_scr |= STM32_DMA_SCR_EN;
+	stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), reg->dma_scr);
+
+	chan->busy = true;
+
+	dev_dbg(chan2dev(chan), "vchan %pK: started\n", &chan->vchan);
+}
+
+static void stm32_dma_configure_next_sg(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	struct stm32_dma_sg_req *sg_req;
+	u32 dma_scr, dma_sm0ar, dma_sm1ar, id;
+
+	id = chan->id;
+	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
+
+	if (dma_scr & STM32_DMA_SCR_DBM) {
+		if (chan->next_sg == chan->desc->num_sgs)
+			chan->next_sg = 0;
+
+		sg_req = &chan->desc->sg_req[chan->next_sg];
+
+		if (dma_scr & STM32_DMA_SCR_CT) {
+			dma_sm0ar = sg_req->chan_reg.dma_sm0ar;
+			stm32_dma_write(dmadev, STM32_DMA_SM0AR(id), dma_sm0ar);
+			dev_dbg(chan2dev(chan), "CT=1 <=> SM0AR: 0x%08x\n",
+				stm32_dma_read(dmadev, STM32_DMA_SM0AR(id)));
+		} else {
+			dma_sm1ar = sg_req->chan_reg.dma_sm1ar;
+			stm32_dma_write(dmadev, STM32_DMA_SM1AR(id), dma_sm1ar);
+			dev_dbg(chan2dev(chan), "CT=0 <=> SM1AR: 0x%08x\n",
+				stm32_dma_read(dmadev, STM32_DMA_SM1AR(id)));
+		}
+	}
+}
+
+static void stm32_dma_handle_chan_done(struct stm32_dma_chan *chan)
+{
+	if (chan->desc) {
+		if (chan->desc->cyclic) {
+			vchan_cyclic_callback(&chan->desc->vdesc);
+			chan->next_sg++;
+			stm32_dma_configure_next_sg(chan);
+		} else {
+			chan->busy = false;
+			if (chan->next_sg == chan->desc->num_sgs) {
+				vchan_cookie_complete(&chan->desc->vdesc);
+				chan->desc = NULL;
+			}
+			stm32_dma_start_transfer(chan);
+		}
+	}
+}
+
+static irqreturn_t stm32_dma_chan_irq(int irq, void *devid)
+{
+	struct stm32_dma_chan *chan = devid;
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	u32 status, scr, sfcr;
+
+	spin_lock(&chan->vchan.lock);
+
+	status = stm32_dma_irq_status(chan);
+	scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+	sfcr = stm32_dma_read(dmadev, STM32_DMA_SFCR(chan->id));
+
+	if (status & STM32_DMA_TCI) {
+		stm32_dma_irq_clear(chan, STM32_DMA_TCI);
+		if (scr & STM32_DMA_SCR_TCIE)
+			stm32_dma_handle_chan_done(chan);
+		status &= ~STM32_DMA_TCI;
+	}
+	if (status & STM32_DMA_HTI) {
+		stm32_dma_irq_clear(chan, STM32_DMA_HTI);
+		status &= ~STM32_DMA_HTI;
+	}
+	if (status & STM32_DMA_FEI) {
+		stm32_dma_irq_clear(chan, STM32_DMA_FEI);
+		status &= ~STM32_DMA_FEI;
+		if (sfcr & STM32_DMA_SFCR_FEIE) {
+			if (!(scr & STM32_DMA_SCR_EN))
+				dev_err(chan2dev(chan), "FIFO Error\n");
+			else
+				dev_dbg(chan2dev(chan), "FIFO over/underrun\n");
+		}
+	}
+	if (status & STM32_DMA_DMEI) {
+		stm32_dma_irq_clear(chan, STM32_DMA_DMEI);
+		status &= ~STM32_DMA_DMEI;
+		if (sfcr & STM32_DMA_SCR_DMEIE)
+			dev_dbg(chan2dev(chan), "Direct mode overrun\n");
+	}
+	if (status) {
+		stm32_dma_irq_clear(chan, status);
+		dev_err(chan2dev(chan), "DMA error: status=0x%08x\n", status);
+		if (!(scr & STM32_DMA_SCR_EN))
+			dev_err(chan2dev(chan), "chan disabled by HW\n");
+	}
+
+	spin_unlock(&chan->vchan.lock);
+
+	return IRQ_HANDLED;
+}
+
+static void stm32_dma_issue_pending(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	if (vchan_issue_pending(&chan->vchan) && !chan->desc && !chan->busy) {
+		dev_dbg(chan2dev(chan), "vchan %pK: issued\n", &chan->vchan);
+		stm32_dma_start_transfer(chan);
+
+	}
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+}
+
+static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
+				    enum dma_transfer_direction direction,
+				    enum dma_slave_buswidth *buswidth,
+				    u32 buf_len)
+{
+	enum dma_slave_buswidth src_addr_width, dst_addr_width;
+	int src_bus_width, dst_bus_width;
+	int src_burst_size, dst_burst_size;
+	u32 src_maxburst, dst_maxburst, src_best_burst, dst_best_burst;
+	u32 dma_scr, fifoth;
+
+	src_addr_width = chan->dma_sconfig.src_addr_width;
+	dst_addr_width = chan->dma_sconfig.dst_addr_width;
+	src_maxburst = chan->dma_sconfig.src_maxburst;
+	dst_maxburst = chan->dma_sconfig.dst_maxburst;
+	fifoth = chan->threshold;
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		/* Set device data size */
+		dst_bus_width = stm32_dma_get_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return dst_bus_width;
+
+		/* Set device burst size */
+		dst_best_burst = stm32_dma_get_best_burst(buf_len,
+							  dst_maxburst,
+							  fifoth,
+							  dst_addr_width);
+
+		dst_burst_size = stm32_dma_get_burst(chan, dst_best_burst);
+		if (dst_burst_size < 0)
+			return dst_burst_size;
+
+		/* Set memory data size */
+		src_addr_width = stm32_dma_get_max_width(buf_len, fifoth);
+		chan->mem_width = src_addr_width;
+		src_bus_width = stm32_dma_get_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return src_bus_width;
+
+		/* Set memory burst size */
+		src_maxburst = STM32_DMA_MAX_BURST;
+		src_best_burst = stm32_dma_get_best_burst(buf_len,
+							  src_maxburst,
+							  fifoth,
+							  src_addr_width);
+		src_burst_size = stm32_dma_get_burst(chan, src_best_burst);
+		if (src_burst_size < 0)
+			return src_burst_size;
+
+		dma_scr = STM32_DMA_SCR_DIR(STM32_DMA_MEM_TO_DEV) |
+			STM32_DMA_SCR_PSIZE(dst_bus_width) |
+			STM32_DMA_SCR_MSIZE(src_bus_width) |
+			STM32_DMA_SCR_PBURST(dst_burst_size) |
+			STM32_DMA_SCR_MBURST(src_burst_size);
+
+		/* Set FIFO threshold */
+		chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_FTH_MASK;
+		if (fifoth != STM32_DMA_FIFO_THRESHOLD_NONE)
+			chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(fifoth);
+
+		/* Set peripheral address */
+		chan->chan_reg.dma_spar = chan->dma_sconfig.dst_addr;
+		*buswidth = dst_addr_width;
+		break;
+
+	case DMA_DEV_TO_MEM:
+		/* Set device data size */
+		src_bus_width = stm32_dma_get_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return src_bus_width;
+
+		/* Set device burst size */
+		src_best_burst = stm32_dma_get_best_burst(buf_len,
+							  src_maxburst,
+							  fifoth,
+							  src_addr_width);
+		chan->mem_burst = src_best_burst;
+		src_burst_size = stm32_dma_get_burst(chan, src_best_burst);
+		if (src_burst_size < 0)
+			return src_burst_size;
+
+		/* Set memory data size */
+		dst_addr_width = stm32_dma_get_max_width(buf_len, fifoth);
+		chan->mem_width = dst_addr_width;
+		dst_bus_width = stm32_dma_get_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return dst_bus_width;
+
+		/* Set memory burst size */
+		dst_maxburst = STM32_DMA_MAX_BURST;
+		dst_best_burst = stm32_dma_get_best_burst(buf_len,
+							  dst_maxburst,
+							  fifoth,
+							  dst_addr_width);
+		chan->mem_burst = dst_best_burst;
+		dst_burst_size = stm32_dma_get_burst(chan, dst_best_burst);
+		if (dst_burst_size < 0)
+			return dst_burst_size;
+
+		dma_scr = STM32_DMA_SCR_DIR(STM32_DMA_DEV_TO_MEM) |
+			STM32_DMA_SCR_PSIZE(src_bus_width) |
+			STM32_DMA_SCR_MSIZE(dst_bus_width) |
+			STM32_DMA_SCR_PBURST(src_burst_size) |
+			STM32_DMA_SCR_MBURST(dst_burst_size);
+
+		/* Set FIFO threshold */
+		chan->chan_reg.dma_sfcr &= ~STM32_DMA_SFCR_FTH_MASK;
+		if (fifoth != STM32_DMA_FIFO_THRESHOLD_NONE)
+			chan->chan_reg.dma_sfcr |= STM32_DMA_SFCR_FTH(fifoth);
+
+		/* Set peripheral address */
+		chan->chan_reg.dma_spar = chan->dma_sconfig.src_addr;
+		*buswidth = chan->dma_sconfig.src_addr_width;
+		break;
+
+	default:
+		dev_err(chan2dev(chan), "Dma direction is not supported\n");
+		return -EINVAL;
+	}
+
+	stm32_dma_set_fifo_config(chan, src_best_burst, dst_best_burst);
+
+	/* Set DMA control register */
+	chan->chan_reg.dma_scr &= ~(STM32_DMA_SCR_DIR_MASK |
+			STM32_DMA_SCR_PSIZE_MASK | STM32_DMA_SCR_MSIZE_MASK |
+			STM32_DMA_SCR_PBURST_MASK | STM32_DMA_SCR_MBURST_MASK);
+	chan->chan_reg.dma_scr |= dma_scr;
+
+	return 0;
+}
+
+static void stm32_dma_clear_reg(struct stm32_dma_chan_reg *regs)
+{
+	memset(regs, 0, sizeof(struct stm32_dma_chan_reg));
+}
+
+static struct dma_async_tx_descriptor *stm32_dma_prep_slave_sg(
+	struct dma_chan *c, struct scatterlist *sgl,
+	u32 sg_len, enum dma_transfer_direction direction,
+	unsigned long flags, void *context)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_desc *desc;
+	struct scatterlist *sg;
+	enum dma_slave_buswidth buswidth;
+	u32 nb_data_items;
+	int i, ret;
+
+	if (!chan->config_init) {
+		dev_err(chan2dev(chan), "dma channel is not configured\n");
+		return NULL;
+	}
+
+	if (sg_len < 1) {
+		dev_err(chan2dev(chan), "Invalid segment length %d\n", sg_len);
+		return NULL;
+	}
+
+	desc = kzalloc(struct_size(desc, sg_req, sg_len), GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	/* Set peripheral flow controller */
+	if (chan->dma_sconfig.device_fc)
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_PFCTRL;
+	else
+		chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_PFCTRL;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		ret = stm32_dma_set_xfer_param(chan, direction, &buswidth,
+					       sg_dma_len(sg));
+		if (ret < 0)
+			goto err;
+
+		desc->sg_req[i].len = sg_dma_len(sg);
+
+		nb_data_items = desc->sg_req[i].len / buswidth;
+		if (nb_data_items > STM32_DMA_ALIGNED_MAX_DATA_ITEMS) {
+			dev_err(chan2dev(chan), "nb items not supported\n");
+			goto err;
+		}
+
+		stm32_dma_clear_reg(&desc->sg_req[i].chan_reg);
+		desc->sg_req[i].chan_reg.dma_scr = chan->chan_reg.dma_scr;
+		desc->sg_req[i].chan_reg.dma_sfcr = chan->chan_reg.dma_sfcr;
+		desc->sg_req[i].chan_reg.dma_spar = chan->chan_reg.dma_spar;
+		desc->sg_req[i].chan_reg.dma_sm0ar = sg_dma_address(sg);
+		desc->sg_req[i].chan_reg.dma_sm1ar = sg_dma_address(sg);
+		desc->sg_req[i].chan_reg.dma_sndtr = nb_data_items;
+	}
+
+	desc->num_sgs = sg_len;
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+
+err:
+	kfree(desc);
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *stm32_dma_prep_dma_cyclic(
+	struct dma_chan *c, dma_addr_t buf_addr, size_t buf_len,
+	size_t period_len, enum dma_transfer_direction direction,
+	unsigned long flags)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_desc *desc;
+	enum dma_slave_buswidth buswidth;
+	u32 num_periods, nb_data_items;
+	int i, ret;
+
+	if (!buf_len || !period_len) {
+		dev_err(chan2dev(chan), "Invalid buffer/period len\n");
+		return NULL;
+	}
+
+	if (!chan->config_init) {
+		dev_err(chan2dev(chan), "dma channel is not configured\n");
+		return NULL;
+	}
+
+	if (buf_len % period_len) {
+		dev_err(chan2dev(chan), "buf_len not multiple of period_len\n");
+		return NULL;
+	}
+
+	/*
+	 * We allow to take more number of requests till DMA is
+	 * not started. The driver will loop over all requests.
+	 * Once DMA is started then new requests can be queued only after
+	 * terminating the DMA.
+	 */
+	if (chan->busy) {
+		dev_err(chan2dev(chan), "Request not allowed when dma busy\n");
+		return NULL;
+	}
+
+	ret = stm32_dma_set_xfer_param(chan, direction, &buswidth, period_len);
+	if (ret < 0)
+		return NULL;
+
+	nb_data_items = period_len / buswidth;
+	if (nb_data_items > STM32_DMA_ALIGNED_MAX_DATA_ITEMS) {
+		dev_err(chan2dev(chan), "number of items not supported\n");
+		return NULL;
+	}
+
+	/*  Enable Circular mode or double buffer mode */
+	if (buf_len == period_len)
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_CIRC;
+	else
+		chan->chan_reg.dma_scr |= STM32_DMA_SCR_DBM;
+
+	/* Clear periph ctrl if client set it */
+	chan->chan_reg.dma_scr &= ~STM32_DMA_SCR_PFCTRL;
+
+	num_periods = buf_len / period_len;
+
+	desc = kzalloc(struct_size(desc, sg_req, num_periods), GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	for (i = 0; i < num_periods; i++) {
+		desc->sg_req[i].len = period_len;
+
+		stm32_dma_clear_reg(&desc->sg_req[i].chan_reg);
+		desc->sg_req[i].chan_reg.dma_scr = chan->chan_reg.dma_scr;
+		desc->sg_req[i].chan_reg.dma_sfcr = chan->chan_reg.dma_sfcr;
+		desc->sg_req[i].chan_reg.dma_spar = chan->chan_reg.dma_spar;
+		desc->sg_req[i].chan_reg.dma_sm0ar = buf_addr;
+		desc->sg_req[i].chan_reg.dma_sm1ar = buf_addr;
+		desc->sg_req[i].chan_reg.dma_sndtr = nb_data_items;
+		buf_addr += period_len;
+	}
+
+	desc->num_sgs = num_periods;
+	desc->cyclic = true;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static struct dma_async_tx_descriptor *stm32_dma_prep_dma_memcpy(
+	struct dma_chan *c, dma_addr_t dest,
+	dma_addr_t src, size_t len, unsigned long flags)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	enum dma_slave_buswidth max_width;
+	struct stm32_dma_desc *desc;
+	size_t xfer_count, offset;
+	u32 num_sgs, best_burst, dma_burst, threshold;
+	int i;
+
+	num_sgs = DIV_ROUND_UP(len, STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
+	desc = kzalloc(struct_size(desc, sg_req, num_sgs), GFP_NOWAIT);
+	if (!desc)
+		return NULL;
+
+	threshold = chan->threshold;
+
+	for (offset = 0, i = 0; offset < len; offset += xfer_count, i++) {
+		xfer_count = min_t(size_t, len - offset,
+				   STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
+
+		/* Compute best burst size */
+		max_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+		best_burst = stm32_dma_get_best_burst(len, STM32_DMA_MAX_BURST,
+						      threshold, max_width);
+		dma_burst = stm32_dma_get_burst(chan, best_burst);
+
+		stm32_dma_clear_reg(&desc->sg_req[i].chan_reg);
+		desc->sg_req[i].chan_reg.dma_scr =
+			STM32_DMA_SCR_DIR(STM32_DMA_MEM_TO_MEM) |
+			STM32_DMA_SCR_PBURST(dma_burst) |
+			STM32_DMA_SCR_MBURST(dma_burst) |
+			STM32_DMA_SCR_MINC |
+			STM32_DMA_SCR_PINC |
+			STM32_DMA_SCR_TCIE |
+			STM32_DMA_SCR_TEIE;
+		desc->sg_req[i].chan_reg.dma_sfcr |= STM32_DMA_SFCR_MASK;
+		desc->sg_req[i].chan_reg.dma_sfcr |=
+			STM32_DMA_SFCR_FTH(threshold);
+		desc->sg_req[i].chan_reg.dma_spar = src + offset;
+		desc->sg_req[i].chan_reg.dma_sm0ar = dest + offset;
+		desc->sg_req[i].chan_reg.dma_sndtr = xfer_count;
+		desc->sg_req[i].len = xfer_count;
+	}
+
+	desc->num_sgs = num_sgs;
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+}
+
+static u32 stm32_dma_get_remaining_bytes(struct stm32_dma_chan *chan)
+{
+	u32 dma_scr, width, ndtr;
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+
+	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
+	width = STM32_DMA_SCR_PSIZE_GET(dma_scr);
+	ndtr = stm32_dma_read(dmadev, STM32_DMA_SNDTR(chan->id));
+
+	return ndtr << width;
+}
+
+/**
+ * stm32_dma_is_current_sg - check that expected sg_req is currently transferred
+ * @chan: dma channel
+ *
+ * This function called when IRQ are disable, checks that the hardware has not
+ * switched on the next transfer in double buffer mode. The test is done by
+ * comparing the next_sg memory address with the hardware related register
+ * (based on CT bit value).
+ *
+ * Returns true if expected current transfer is still running or double
+ * buffer mode is not activated.
+ */
+static bool stm32_dma_is_current_sg(struct stm32_dma_chan *chan)
+{
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	struct stm32_dma_sg_req *sg_req;
+	u32 dma_scr, dma_smar, id;
+
+	id = chan->id;
+	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
+
+	if (!(dma_scr & STM32_DMA_SCR_DBM))
+		return true;
+
+	sg_req = &chan->desc->sg_req[chan->next_sg];
+
+	if (dma_scr & STM32_DMA_SCR_CT) {
+		dma_smar = stm32_dma_read(dmadev, STM32_DMA_SM0AR(id));
+		return (dma_smar == sg_req->chan_reg.dma_sm0ar);
+	}
+
+	dma_smar = stm32_dma_read(dmadev, STM32_DMA_SM1AR(id));
+
+	return (dma_smar == sg_req->chan_reg.dma_sm1ar);
+}
+
+static size_t stm32_dma_desc_residue(struct stm32_dma_chan *chan,
+				     struct stm32_dma_desc *desc,
+				     u32 next_sg)
+{
+	u32 modulo, burst_size;
+	u32 residue;
+	u32 n_sg = next_sg;
+	struct stm32_dma_sg_req *sg_req = &chan->desc->sg_req[chan->next_sg];
+	int i;
+
+	/*
+	 * Calculate the residue means compute the descriptors
+	 * information:
+	 * - the sg_req currently transferred
+	 * - the Hardware remaining position in this sg (NDTR bits field).
+	 *
+	 * A race condition may occur if DMA is running in cyclic or double
+	 * buffer mode, since the DMA register are automatically reloaded at end
+	 * of period transfer. The hardware may have switched to the next
+	 * transfer (CT bit updated) just before the position (SxNDTR reg) is
+	 * read.
+	 * In this case the SxNDTR reg could (or not) correspond to the new
+	 * transfer position, and not the expected one.
+	 * The strategy implemented in the stm32 driver is to:
+	 *  - read the SxNDTR register
+	 *  - crosscheck that hardware is still in current transfer.
+	 * In case of switch, we can assume that the DMA is at the beginning of
+	 * the next transfer. So we approximate the residue in consequence, by
+	 * pointing on the beginning of next transfer.
+	 *
+	 * This race condition doesn't apply for none cyclic mode, as double
+	 * buffer is not used. In such situation registers are updated by the
+	 * software.
+	 */
+
+	residue = stm32_dma_get_remaining_bytes(chan);
+
+	if (!stm32_dma_is_current_sg(chan)) {
+		n_sg++;
+		if (n_sg == chan->desc->num_sgs)
+			n_sg = 0;
+		residue = sg_req->len;
+	}
+
+	/*
+	 * In cyclic mode, for the last period, residue = remaining bytes
+	 * from NDTR,
+	 * else for all other periods in cyclic mode, and in sg mode,
+	 * residue = remaining bytes from NDTR + remaining
+	 * periods/sg to be transferred
+	 */
+	if (!chan->desc->cyclic || n_sg != 0)
+		for (i = n_sg; i < desc->num_sgs; i++)
+			residue += desc->sg_req[i].len;
+
+	if (!chan->mem_burst)
+		return residue;
+
+	burst_size = chan->mem_burst * chan->mem_width;
+	modulo = residue % burst_size;
+	if (modulo)
+		residue = residue - modulo + burst_size;
+
+	return residue;
+}
+
+static enum dma_status stm32_dma_tx_status(struct dma_chan *c,
+					   dma_cookie_t cookie,
+					   struct dma_tx_state *state)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct virt_dma_desc *vdesc;
+	enum dma_status status;
+	unsigned long flags;
+	u32 residue = 0;
+
+	status = dma_cookie_status(c, cookie, state);
+	if (status == DMA_COMPLETE || !state)
+		return status;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	vdesc = vchan_find_desc(&chan->vchan, cookie);
+	if (chan->desc && cookie == chan->desc->vdesc.tx.cookie)
+		residue = stm32_dma_desc_residue(chan, chan->desc,
+						 chan->next_sg);
+	else if (vdesc)
+		residue = stm32_dma_desc_residue(chan,
+						 to_stm32_dma_desc(vdesc), 0);
+	dma_set_residue(state, residue);
+
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	return status;
+}
+
+static int stm32_dma_alloc_chan_resources(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	int ret;
+
+	chan->config_init = false;
+
+	ret = pm_runtime_resume_and_get(dmadev->ddev.dev);
+	if (ret < 0)
+		return ret;
+
+	ret = stm32_dma_disable_chan(chan);
+	if (ret < 0)
+		pm_runtime_put(dmadev->ddev.dev);
+
+	return ret;
+}
+
+static void stm32_dma_free_chan_resources(struct dma_chan *c)
+{
+	struct stm32_dma_chan *chan = to_stm32_dma_chan(c);
+	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
+	unsigned long flags;
+
+	dev_dbg(chan2dev(chan), "Freeing channel %d\n", chan->id);
+
+	if (chan->busy) {
+		spin_lock_irqsave(&chan->vchan.lock, flags);
+		stm32_dma_stop(chan);
+		chan->desc = NULL;
+		spin_unlock_irqrestore(&chan->vchan.lock, flags);
+	}
+
+	pm_runtime_put(dmadev->ddev.dev);
+
+	vchan_free_chan_resources(to_virt_chan(c));
+}
+
+static void stm32_dma_desc_free(struct virt_dma_desc *vdesc)
+{
+	kfree(container_of(vdesc, struct stm32_dma_desc, vdesc));
+}
+
+static void stm32_dma_set_config(struct stm32_dma_chan *chan,
+				 struct stm32_dma_cfg *cfg)
+{
+	stm32_dma_clear_reg(&chan->chan_reg);
+
+	chan->chan_reg.dma_scr = cfg->stream_config & STM32_DMA_SCR_CFG_MASK;
+	chan->chan_reg.dma_scr |= STM32_DMA_SCR_REQ(cfg->request_line);
+
+	/* Enable Interrupts  */
+	chan->chan_reg.dma_scr |= STM32_DMA_SCR_TEIE | STM32_DMA_SCR_TCIE;
+
+	chan->threshold = STM32_DMA_THRESHOLD_FTR_GET(cfg->features);
+	if (STM32_DMA_DIRECT_MODE_GET(cfg->features))
+		chan->threshold = STM32_DMA_FIFO_THRESHOLD_NONE;
+}
+
+static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
+					   struct of_dma *ofdma)
+{
+	struct stm32_dma_device *dmadev = ofdma->of_dma_data;
+	struct device *dev = dmadev->ddev.dev;
+	struct stm32_dma_cfg cfg;
+	struct stm32_dma_chan *chan;
+	struct dma_chan *c;
+
+	if (dma_spec->args_count < 4) {
+		dev_err(dev, "Bad number of cells\n");
+		return NULL;
+	}
+
+	cfg.channel_id = dma_spec->args[0];
+	cfg.request_line = dma_spec->args[1];
+	cfg.stream_config = dma_spec->args[2];
+	cfg.features = dma_spec->args[3];
+
+	if (cfg.channel_id >= STM32_DMA_MAX_CHANNELS ||
+	    cfg.request_line >= STM32_DMA_MAX_REQUEST_ID) {
+		dev_err(dev, "Bad channel and/or request id\n");
+		return NULL;
+	}
+
+	chan = &dmadev->chan[cfg.channel_id];
+
+	c = dma_get_slave_channel(&chan->vchan.chan);
+	if (!c) {
+		dev_err(dev, "No more channels available\n");
+		return NULL;
+	}
+
+	stm32_dma_set_config(chan, &cfg);
+
+	return c;
+}
+
+static const struct of_device_id stm32_dma_of_match[] = {
+	{ .compatible = "st,stm32-dma", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, stm32_dma_of_match);
+
+static int stm32_dma_probe(struct platform_device *pdev)
+{
+	struct stm32_dma_chan *chan;
+	struct stm32_dma_device *dmadev;
+	struct dma_device *dd;
+	const struct of_device_id *match;
+	struct resource *res;
+	struct reset_control *rst;
+	int i, ret;
+
+	match = of_match_device(stm32_dma_of_match, &pdev->dev);
+	if (!match) {
+		dev_err(&pdev->dev, "Error: No device match found\n");
+		return -ENODEV;
+	}
+
+	dmadev = devm_kzalloc(&pdev->dev, sizeof(*dmadev), GFP_KERNEL);
+	if (!dmadev)
+		return -ENOMEM;
+
+	dd = &dmadev->ddev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dmadev->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(dmadev->base))
+		return PTR_ERR(dmadev->base);
+
+	dmadev->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dmadev->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(dmadev->clk), "Can't get clock\n");
+
+	ret = clk_prepare_enable(dmadev->clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "clk_prep_enable error: %d\n", ret);
+		return ret;
+	}
+
+	dmadev->mem2mem = of_property_read_bool(pdev->dev.of_node,
+						"st,mem2mem");
+
+	rst = devm_reset_control_get(&pdev->dev, NULL);
+	if (IS_ERR(rst)) {
+		ret = PTR_ERR(rst);
+		if (ret == -EPROBE_DEFER)
+			goto clk_free;
+	} else {
+		reset_control_assert(rst);
+		udelay(2);
+		reset_control_deassert(rst);
+	}
+
+	dma_set_max_seg_size(&pdev->dev, STM32_DMA_ALIGNED_MAX_DATA_ITEMS);
+
+	dma_cap_set(DMA_SLAVE, dd->cap_mask);
+	dma_cap_set(DMA_PRIVATE, dd->cap_mask);
+	dma_cap_set(DMA_CYCLIC, dd->cap_mask);
+	dd->device_alloc_chan_resources = stm32_dma_alloc_chan_resources;
+	dd->device_free_chan_resources = stm32_dma_free_chan_resources;
+	dd->device_tx_status = stm32_dma_tx_status;
+	dd->device_issue_pending = stm32_dma_issue_pending;
+	dd->device_prep_slave_sg = stm32_dma_prep_slave_sg;
+	dd->device_prep_dma_cyclic = stm32_dma_prep_dma_cyclic;
+	dd->device_config = stm32_dma_slave_config;
+	dd->device_terminate_all = stm32_dma_terminate_all;
+	dd->device_synchronize = stm32_dma_synchronize;
+	dd->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+		BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	dd->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
+		BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
+		BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	dd->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	dd->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+	dd->copy_align = DMAENGINE_ALIGN_32_BYTES;
+	dd->max_burst = STM32_DMA_MAX_BURST;
+	dd->descriptor_reuse = true;
+	dd->dev = &pdev->dev;
+	INIT_LIST_HEAD(&dd->channels);
+
+	if (dmadev->mem2mem) {
+		dma_cap_set(DMA_MEMCPY, dd->cap_mask);
+		dd->device_prep_dma_memcpy = stm32_dma_prep_dma_memcpy;
+		dd->directions |= BIT(DMA_MEM_TO_MEM);
+	}
+
+	for (i = 0; i < STM32_DMA_MAX_CHANNELS; i++) {
+		chan = &dmadev->chan[i];
+		chan->id = i;
+		chan->vchan.desc_free = stm32_dma_desc_free;
+		vchan_init(&chan->vchan, dd);
+	}
+
+	ret = dma_async_device_register(dd);
+	if (ret)
+		goto clk_free;
+
+	for (i = 0; i < STM32_DMA_MAX_CHANNELS; i++) {
+		chan = &dmadev->chan[i];
+		ret = platform_get_irq(pdev, i);
+		if (ret < 0)
+			goto err_unregister;
+		chan->irq = ret;
+
+		ret = devm_request_irq(&pdev->dev, chan->irq,
+				       stm32_dma_chan_irq, 0,
+				       dev_name(chan2dev(chan)), chan);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"request_irq failed with err %d channel %d\n",
+				ret, i);
+			goto err_unregister;
+		}
+	}
+
+	ret = of_dma_controller_register(pdev->dev.of_node,
+					 stm32_dma_of_xlate, dmadev);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+			"STM32 DMA DMA OF registration failed %d\n", ret);
+		goto err_unregister;
+	}
+
+	platform_set_drvdata(pdev, dmadev);
+
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_get_noresume(&pdev->dev);
+	pm_runtime_put(&pdev->dev);
+
+	dev_info(&pdev->dev, "STM32 DMA driver registered\n");
+
+	return 0;
+
+err_unregister:
+	dma_async_device_unregister(dd);
+clk_free:
+	clk_disable_unprepare(dmadev->clk);
+
+	return ret;
+}
+
+#ifdef CONFIG_PM
+static int stm32_dma_runtime_suspend(struct device *dev)
+{
+	struct stm32_dma_device *dmadev = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(dmadev->clk);
+
+	return 0;
+}
+
+static int stm32_dma_runtime_resume(struct device *dev)
+{
+	struct stm32_dma_device *dmadev = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(dmadev->clk);
+	if (ret) {
+		dev_err(dev, "failed to prepare_enable clock\n");
+		return ret;
+	}
+
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_PM_SLEEP
+static int stm32_dma_suspend(struct device *dev)
+{
+	struct stm32_dma_device *dmadev = dev_get_drvdata(dev);
+	int id, ret, scr;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0)
+		return ret;
+
+	for (id = 0; id < STM32_DMA_MAX_CHANNELS; id++) {
+		scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
+		if (scr & STM32_DMA_SCR_EN) {
+			dev_warn(dev, "Suspend is prevented by Chan %i\n", id);
+			return -EBUSY;
+		}
+	}
+
+	pm_runtime_put_sync(dev);
+
+	pm_runtime_force_suspend(dev);
+
+	return 0;
+}
+
+static int stm32_dma_resume(struct device *dev)
+{
+	return pm_runtime_force_resume(dev);
+}
+#endif
+
+static const struct dev_pm_ops stm32_dma_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_dma_suspend, stm32_dma_resume)
+	SET_RUNTIME_PM_OPS(stm32_dma_runtime_suspend,
+			   stm32_dma_runtime_resume, NULL)
+};
+
+static struct platform_driver stm32_dma_driver = {
+	.driver = {
+		.name = "stm32-dma",
+		.of_match_table = stm32_dma_of_match,
+		.pm = &stm32_dma_pm_ops,
+	},
+	.probe = stm32_dma_probe,
+};
+
+static int __init stm32_dma_init(void)
+{
+	return platform_driver_register(&stm32_dma_driver);
+}
+subsys_initcall(stm32_dma_init);